Same here, I binge-watched the entire TV series by this time last year and have re-watched several episodes ever since. As everyone, I noticed how weird the show got from season 5 upwards although I didn't dwell into it that much. Cersei became pretty much my favorite character, even so before I started watching the show as a whole just by looking at clips of her.
And so I looked at her ADwD POV chapters just to know what was going through her mind during the walk, and then I couldn't get enough of her so I looked at her AFfC chapters as well: exquisite, hilarious, scary, infuriating, bold and MUCH more all at once. I was shook, still am, and couldn't help but notice how wholesome everything is compared to the show. Everything that happens has a reason and isn't just there as a plot device. I looked for reviews on her chapters and some youtuber mentioned The Fandomentals and how Cersei (née: Carol/Cheryl) is a central point of discussion for them, I went there and read a lot of articles from them and realized how pointless/dumb the majority of the show is.
After all that, is that I started to read the books proper. Currently, I'm more than a half in ACoK.